rollback scikit-learn version

Author: jbrightuniverse

environment.yml

@@ -22,7 +22,7 @@ dependencies:
     - pyarrow
     - xgboost
     - graphviz
-    - scikit-learn >= 0.24.0
+    - scikit-learn >= 0.24.0,<1.0
     - bokeh
     - sphinxcontrib-bibtex
     - quantecon-book-theme>=0.2.5,<0.3.0